Ventilating system for telephone booths



Oct. 19, 1943. J, J, KUHN 2,332,091

VENTILATING SYSTEM FOR TELEPHONE BOOTHS Filed May 3, 1941 2 Sheets-Sheetl /NVENTOR J. J. KUHN By Qu/KM ATTORNEY 0d. 19, 1943. 9.1. KUHN2,332,091

VENTILATING SYSTEM FOR TELEPHONE BOOTHS Filed May 5, 1941 2 Sheets-Sheet2 40 47 ni U 32 34 '.:|I O 45/ 46 bf .u u 33 /N VEN TOR J. J. KUHN EL@@QCM/L51( ATTORNEY Patented ()ct. 19, 1943 U NI'TEDY STATES PATENTOFFICE VENTILATIN G SYSTEM FOR TELEPHONE BOOTHS Application May 3',1941, Serial No. 391,661

7 Claims.

This invention relates to telephone booths and more particularly to thetype of booth which is ventilated by a motor-driven fan controlled bythe operation of the booth door.

In telephone booths now in use the fan which is installed therein forthe purpose of Ventilating the booth is automatically turned on when thebooth door is closed andautomatically turned oi when the booth door isopened.

The object of the present invention is the provision of a telephonebooth in which the vitiated air in the booth is expelled after theoccupant leaves the booth and the door is opened, so that fresh air isprovided, for thev next patron.

`In accordance with this invention the fan is maintained in operationafter the booth door is opened for av predetermined interval of timeinstead of being shut oi bythe opening of the-door as in booths now inuse. l

In the preferred ormof my invention, I locate adjacent the lamp inthebooth, which is automatically. lightedwhen the booth door is closed and,extinguished when the door is opened, aY

thermostatically controlled switch which due to the heat absorbed fromthe lamp when it is light-` ed, maintains the fan in operation after itis extinguished and the door is opened. The length of time that the fanwill remain in operation is directly proportional to the length of timethat the booth is iny use, i. e., the longer the lamp burns, the longerthe fan willoperate after the door is opened. The length of time thatthe fan will run after the booth is vacated can be Vreadily controlledwithin certain limits by the adjustment of the thermostatic switch.

In a modied form of my invention I have provided a pair of mercuryswitches, one for controlling the turning on and off of the lamp and theother for controlling the operation of the fan. I have connected inparallel with the lamp a resistance element which increases the currentflow through the. bimetallic element. This bimetallic element links theswitches together so that they operate as a unit when the door isclosed, but not when it is opened. Due to the current passing throughthe bimetallic element, heat is generated therein which causes it toexpand, thereby maintaining the fan switch closed and the fan inoperation alter the lamp has been extinguished and the door opened. Asthe heat is dissipated froml the bimetallic element it will return tonormal, tilt the mercury switch to the o position and stop the fan,

The features of my invention will be readily apparent from the followingdetailed description made with reference to the following drawings, ofwhich:

Fig. 1 is a schematic top plan View o a telephone booth with the boothdoor open and the light switch and fan switch in their normal or openposition;

Fig. 2 is a View similar to Fig. l except that the booth door has beenclosed and the light switch and the fan switch have been closed, `thuslighting the lamp and putting the fan in operation;

Fig. 3 is a view similar to Fig. 1 except that the fan switch is closeddue to the thermostatic element, thereby maintaining the fan inoperation with the door open and the light extinguished;

Fig. 4 is a fragmentary perspective view of a modied form of theinvention in which a pair of mercury switches are employed to controlthe operation of the lamp and fan; and

Fig. 5 is a fragmentary View of an alternate circuit arrangement for usewhen the lamp in the booth is independently controlled.

As shown in Fig. 1, the structure of the telephone booth III isindicated by dot and dash lines and is provided at one side with anopening which is adapted to be closed by means of the door II. Securedto the door II and operated thereby is an arm I2, one end of which ispivoted at the door hinge by means of the lever I3 and the other endterminating in a clevis I4 which, in turn is secured to an arm I5 whichis secured to the switch operating mechanism (not shown).

The switch I6 for operating the fan Il and lighting the lamp I3 isschematically shown and comprises, as shown in Fig. l, a pair of levelarms I9 and 29 which are operated by means of the lever I5. A pair ofcooperating contact springs 2I and 22, which when the door II is closed.as shown in Fig. 2, closes a circuit to the fan I`I and the lamp I8 overthe conductor pairs 23, 24 and 25, the circuit including an alternatingcurrent source 25. This causes the lamp I8 to light and the fan I'I tooperate.

Due to the fact that the Contact spring 2l is constructed frombimetallic material, and located close to the lamp 2l, the heat of thelamp will cause it to flex and bear with considerable force againstlever arm IS. Thus when the door II is opened, as shown in Fig. 3, andfor a predetermined interval thereafter the fan Contact will still bemaintained closed due to the pressure of the contact arm 2| against thelever arm I9, while the circuit to the lamp I8 will be broken by theseparation of the contact spring 22 from the lever arm 2B. The fan I'Iwill therefore remain inl operation until the heat absorbed from thelamp |8 by the contact spring 2| is dissipated, when it returns tonormal and opens the circuit, as shown in Fig. l. Thus, it will beobserved that the fan will remain in operation for acertain interval oftime to clear the booth of vitiated air after the light I8 isextinguished and the door is opened.

In the modification shown in Fig. 4, a pair of supports 21 and 28, whichmay be suitably secured in the booth (not shown) have secured thereto arod 29. Rotatably mounted on the rod 29 are a pair of U-shapedinsulating members 30 and 3|. These members are spaced apart and areprovided on their facing surfaces with extending metallic pins 32 and33, respectively.

A bimetallic member 34, having a spiral configuration, is positionedbetween the members 3C and 3| with the inner end of the spiral securedto the pin 33 on the member 3|, and its outer end secured to the pin 32on the member 30. The bimetallic member 34 provides a flexible couplingbetween the two U-shaped members 33 and 3|.

Located in the insulated U-shaped members 30 and 3| are the mercurycontact devices 35 and 36, respectively, one of which (35) controls theoperati-on of the lamp and the energization of the resistance 38 and theother (35) controls the operation of the fan39. When these devices arein their normal positions as shown in Fig. 4 the lamp and fan circuitswill be broken due to the fact that these mercury contact devices areslightly out of level thereby maintaining the mercury in the rear of thetubes and away from the contacts in the opposite ends thereof. It isonly when these devices are tilted that the mercury will run to the endsof the tubes and closes the circuits to light the lamp 31, energize theresistance 38 and start the fan 39.

Secured to the U-shaped member 3!) is an eX- tending arm portion 40 towhich is pivotally secured an arm 4| which in turn is operated by thedoor of the telephone booth (not shown).

As shown in Fig. 4 the contact devices 35 and 3B are in their normal orunoperated position; that is, when the telephone booth door is open.Upon the closing of the door the arm 4| will be actuated thus causingthe U-shaped members 30 and 3| and their Contact devices 35 and 35 torotate on the shaft 39. Due to the fact that these members are coupledtogether by means of the bimetallic member 34, these two mercuryswitches will tilt in. unison thereby closing the circuit to the lamp31, the resistance 38 and the fan 39.

The circuit for lighting the lamp 31 may be traced from one side of thecurrent source 42 over conductor 43, through the lamp 31, over conductor44 to one side of the contact device 35, through the mercury in saidcontact device and the other contact, over the conductor 45 to theterminal 46 on the pin 32, through the pin 32, through the bimetallicstrip 34 through the pin 33 to the terminal 41, through the terminal 41,over conductor 48 to the other side of the current source 42, thuscompleting the circuit to light the lamp 31. The resistance 38 is placedin parallel with the lamp 31 and in series with bimetallic member 34 topermit increased currentI iiow through the bimetallic member.

When the contact device 3S is in its operative or tilted position, asreferred to above, the fan circuit is from one side of the currentsource 42 over conductor 48 through conductor 49 to one side of thecontact device 36, through the mercury in the Contact device to theother contact, through said contact over conductor 50 through the fan 39and back to the current source 42.

While the booth door is closed and current is iiowing through thebimetallic strip it will expand or rather partially straighten out dueto the fact that the inner element of the strip has a higher coefficientof expansion than the outer element. This straightening out eilectcontinues until the limiting stop for the Ushaped member is reached orin case no stop is used, until the limit of expansion of the bimetallicmember 34 f is reached.

When the patron opens the door to leave the booth the arm 4| operated bythe door rocks the U-shaped member 39 carrying the mercury switch 35 toopen the lamp circuit, but the U- shaped member 3|, carrying the mercuryswitch 3S, is not rocked back to normal because of the expandedcondition of the bimetallic strip 34. It is only when this strip hascooled off and tightened the spiral in which it is formed that theU-shaped member 3| is rocked back to normal to tilt the mercury switchwhich it carries to open the fan circuit. This interval of time isdetermined not only by the characteristics of the bimetallic strip, butalso within certain limits by the length of time the booth door has beenclosed.

In some telephone booth installations the lamp, located on the interiorof the booth,'is under the control of an attendant and is not controlledby the opening and closing of the booth door.

For this type of installation a circuit arrangement like that shown inFig. 5 is employed. As shown in Fig. 5 the lighting of the lamp 31 iscontrolled by a manually operated switch 49 and an additional resistance5 l, having the same value as the resistance 38, is connected inparallel therewith, thereby increasing the current flow through thecircuit to heat up the bimetallic eiement in the same manner asheretofore described with regard to the circuit arrangement shown inFig. 4.

While there is shown and described herein the preferred embodiment of myinvention, it is to be understood that it is not limited or confined tothe present details of construction herein described and variousmodifications may be made therein Without departing from the spirit ofthe invention, and I am only limited by the scope of the appendedclaims.

What is claimed is:

l. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure, an electricallydriven fan located in said enclosure to force the ventilation thereof, alamp for illuminating the interior of said enclosure, circuits for saidfan and said lamp, a switch in said circuits having a fan contact springand a lamp contact spring associated therewith, said fan contact springcontrolling the operation of said fan and comiprising a strip ofbimetallic material, both sets of contact springs adapted to close saidfan and lamp circuits to operate said fan and light said lamp by saiddoor when it is closed, said b-i'netallic contact spring iniiuenced bythe heat of said lamp to maintain the fan circuit closed and the fan inoperation after the door is opened and the lamp circuit opened.

2. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure an electricallydriven fan located in said enclosure to force the ventilation thereof, alamp in said enclosure for illuminating the interior of said enclosure,circuits for said fan and said lamp, a switch in said circuits actuatedby said door as it is closed for putting said fan into operation andlighting said lamp, said switch having a plurality of contact springsthereon, one of said springs located in said fan circuit and constructedof bimetallic material and located adjacent said lamp, said contactspring adapted to be influenced by the heat of said lamp to maintain thefan circuit closed and the fan in operation a predetermined length oftime after the door has been opened and the lamp circuit opened.

3. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure, a lamp in saidenclosure, an electrically driven fan located in said enclosure forcirculating the air therein, circuits for said lamp and said fan, aresistance element in said lamp circuit, a pair of switches actuated bysaid door as it is closed for closing said circuits to put said fan intooperation, light said lamp and energize said resistance element, and abimetallic link in said lamp circuit coupling said switches together formaintaining the fan circuit closed and the fan in operation apredetermined length of time after the door has r been opened and thelamp circuit opened by one of said switches, thereby cutting off thecurrent to the resistance element.

4. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure, a lamp in saidenclosure, an electrically driven fan located in said enclosure, toforce the ventilation thereof, circuits for said lamp and said fan, aresistan element in said lamp circuit in parallel with said lamp, amechanism comprising a pair of switch elements, one in the fan circuitfor controlling the operation of the fan and the other in the lampcircuit for controlling said lamp, a bimetallic member coupling saidswitches together and connected in said lamp circuit, said pair ofswitches adapted to be operated to close said circuits to energize theresistance element, light said lamp and to start the fan by said door asit is closed, said bimetallic member inuenced by the increase of currentflowing therethrough` due to the resistance in said lamp circuit, tomaintain the fan circuit closed and the fan in operation by keeping thefan switch closed a predetermined length of time after the door hasventilation thereof, a lamp for illuminating the interior of saidenclosure, circuits for said fan and said lamp, a resistance element insaid lamp circuit in parallel with said lamp, a pair of switchesactuated by said door as it is closed for closing said circuits to putsaid fan into operation, light said lamp and energize said resistanceelement, and bimetallic means in said lamp circuit coupling saidSwitches together for maintaining the fan circuit closed and the fan inoperation a predetermined length of time after the lamp circuit has beenopened by the opening of said door, the resistance element deenergized,and the lamp switch restored to normal, by maintaining the fan switchoperated and the fan circuit closed.

6. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure, an electricallydriven fan located in said enclosure to force the ventilation thereof, alamp for illuminating the interior of said enclosure, circuits for saidfan and said lamp, a resistance element in said lamp circuit and inparallel with said lamp, a switch mechanism connected in said circuitshaving a ian contact element and a lamp contact element associatedtherewith for controlling the operation of said fan and said lamp, saidlamp contact element also controlling the energization of saidresistance element in said lamp circuit, said fan contact element andlamp contact element coupled together by a bimetallic member in saidlamp circuit, said contact elements adapted to close said circuits tooperate said fan, light said lamp and energize said resistance elementby said door as it is closed, said bimetallic coupling member influencedby the heat generated therein by the current passing therethrough tomaintain the switch in the fan circuit closed and the fan in operationafter the door is opened and the circuit to the lamp and resistanceelement opened.

7. A Ventilating system for telephone booths and the like comprising anenclosure, a door for gaining access to said enclosure, an electricallydriven fan located in said enclosure to force the ventilation thereof, alamp for illuminating the interior of said enclosure, circuits for saidfan and said lamp, a resistance element in said lamp circuit and inparallel with said lamp, a switch comprising a pair of mercury contactdevices connected in said circuit and actuated by said door as it isclosed for closing said circuit to put said fan into operation, lightsaid lamp and energize said heating element, and bimetallic means insaid lamp circuit coupling said mercury contact devices together andheated by the current passing therethrough for maintaining one of saidswitches in said circuit closed to maintain the fan in operation apredetermined length of time after the door has been opened, the lampcircuit open and the resistance element deenergized.

JOHN J. KUHN.

